The United States added another $890 million to the Syrian humanitarian aid effort Thursday, pledging increased support for refugee aid.

Addressing a summit of donor nations in London, Kerry said that $600 million (537 million euros) in new funding would go on urgent aid to refugees and beleaguered populations in and around Syria.

Another $290 million will go on development assistance for schooling for refugee children in Jordan and Lebanon.

The figure covers the current US fiscal year, which runs until August, and is in addition to previous contributions.

“The United States has provided over $4.5 billion to help Syrian refugees and those displaced within Syria, and I’m proud that that makes us the largest single external donor in the world,” Kerry said.

The US envoy urged the other countries represented in London to increase their own contributions to help deal with what he said was a “staggering” refugee crisis.

“By helping refugees, we remind ourselves of who we are, what we are against, and what we are for,” he said.

In September, Kerry said, US President Barack Obama will convene a summit on refugees on the sidelines of the United Nations General Assembly.

“Between then and now, we call on the global community to increase by at least thirty percent the overall response to humanitarian funding appeals for refugees,” he said.